Mine also got shipped out today but heh it'll be like a week b4 I'll get them since ordering from abroad. It's gonna have a tough battle against XB500 since I feel it sounds perfectly according to my own taste on pretty much all aspects with the EQ settings applied (I use a really good EQ too mind you). If there's something I don't like about the Pannies it doesn't have to be bad at all, much the same as I know I wouldn't like a Sennheiser HD800 for example (probably not an Ultrasone Pro 900 either), probably hate it.
This is what I want, a very forward / in-your-face sound, it should sound like music is surrounding you, like you're the center of music, similar experience to being on a dancefloor at a nightclub or on the stage of a band, not sounding like you'd be in the crowd further back in the audience (think ATH-AD700/900, Sennheiser HD800, AKG K70x etc) so it seems like it would be a "distance" to the music. At the same time I don't like really poor soundstage, I want that "out-of-head" experience but I want it to sound like I'm the center of the music, it doesn't have to be the biggest soundstage but it should have clear positioning as if you can picture the directions of the sounds coming out of your head though, that's pretty much a requirement (for example AKG K518/81 DJs totally fails IMO on this). Balancewise it seems around ~12dB bass boost is the optimal to me if the ~15dB boost of XB500 is accurate according to headphone.com + innerfidelity as I boost the mids and highs on XB500 a bit so. Then it's important that the bassresponse is as flat as possible from the deepest tones I can hear to the mid/upper bass, maybe around 200~250Hz or so it should start roll-off to avoid muddying up the mids. Meaning I don't like "punchy" nor "loose" bass, I want a good balance between slower deep rumbling bass (DT770 Pro, XB700 are examples of headphones with too much focus on subbass alone for my liking) and punchy fast mid/upper bass (HFI-580, AKG K518, D1100 are examples of too punchy/tight bass for my liking). At the same time I enjoy as forward mids as possible, hardly any headphone seems to have boosted beyond "neutral" mids, I probably even wouldn't mind maybe 3dB boost due to bass being so forward for starters but highs should stay pretty much neutral, tiny bit veiled might even be ok but I dislike emphasized highs as I like my sound warmer as it sounds like "fullier" sound to me, I hate the thin V-shaped sound, I'd much rather have an upside-down V-shaped curve even. There's also other smaller factors that will also impact my satisfaction such as natural reverb/decay of frequencies (I don't like a very dry sound, ie. lack of reverb presence) for example.